/Engine/Source/Runtime/RenderCore/Public/VertexFactory.h
Can be overridden byFVertexFactorysubclasses to modify their compile environment just before compilation occurs.
static void ModifyCompilationEnvironment ( const [FVertexFactoryShaderPermutationParameters](API\Runtime\Renderer\FVertexFactoryShaderPermutationP-) & Parameters, [FShaderCompilerEnvironment](API\Runtime\RenderCore\FShaderCompilerEnvironment) & OutEnvironment )